xdp-trafficgen: Add missing comma in list of drivers

Coverity pointed out that there's a comma missing in the list of
drivers, leading two of the strings to be concatenated instead of being
separate items in the list.

Signed-off-by: Toke Høiland-Jørgensen <[email protected]>

Author: tohojo

xdp-trafficgen/xdp-trafficgen.c

@@ -62,7 +62,7 @@ static const char *driver_pass_list[] = {
 	"i40e",
 	"ice",
 	"igb",
-	"igc"
+	"igc",
 	"ixgbe",
 	"octeontx2",
 	"stmmac",